Sweat houses are a form of rural sauna unique to Ireland. They were common in the north in the 18th century, then died out towards the end of the 19th. Their main function was as a form of healthcare for rural workers in upland areas, where they functioned as curative sites for fever, flu, rheumatism and arthritis.

They look a little like stone igloos, typically about around 1.2m high and 1.8m long, with a small blockable entrance and a hole in the grass or sod roof, to let out smoke from the turf or wood fire.

The patient took off his or her clothes – the normal practice was to take turns using them, with men and women kept apart – and stayed inside for 20 to 30 minutes before being wrapped up and taken home to bed.

The decline of the sweat house after the Famine might have been down to the more scientific medicine brought to the higher country areas by a new network of country doctors and rural dispensaries.

The remains of about 280 sweat houses are still listed in the Sites and Monuments Record, 234 in the Republic, 45 in the North. The map shows their distribution, with clusters around the top of the Shannon catchment, in Leitrim, Fermanagh and neighbouring counties. Elsewhere they are rare, with individual sweat houses found in north Co Tipperary and Co Wicklow.

The best-documented and -preserved sweat house is in Tirkane, near Maghera, where the cure also included a plunge pool by a nearby stream.